The invention discloses a non-destructive detector for an inner wall of a pipe. The non-destructive detector is characterized by structurally comprising a machine body, a control box, a middle fixed plate, a rotary hole, a rotary telescopic pole, a movable column, a movable block, a lifting tube, a non-destructive detecting device, a two-way extruding arm and a rail base, wherein the machine bodyis of a rectangular structure; the front end of the machine body is welded with the middle fixed plate; the control box is arranged on the left end surface of the middle fixed plate and is electrically connected with the machine body; the middle fixed plate is embedded into the front end of the machine body to form an integrated structure; the rotary hole is circular, is embedded into the middle part of the front end of the middle fixed plate and is arranged on the outer part of the rotary telescopic pole; and the rotary telescopic pole penetrates through the rotary hole for connecting the machine body to the non-destructive detecting device. The non-destructive detector has the beneficial effects that: inner wall non-destructive detection can be performed by the non-destructive detector for the inner wall of the pipe according to the diameter size of the pipe, the damage degree is determined by pressure detection and transmission, a probe is equipped for recording, the operation is simple, detecting precision is high, the manufacturing cost is low, and therefore, the non-destructive detector is suitable for large and small pipes, is small in limitation and is convenient to use.